Tooltip: Only bind remove handler for delegated tooltips

[scottgonzalez]

The remove handler was being added for every tooltip, but only removed for
delegated tooltips. The default destroy behavior already handles non-delegated
tooltips, so the handler should only be added for delegated tooltips.

Fixes #9531

I'm not sure if there's a reasonable way to test this. We don't generally test for memory leaks.

[tjvantoll]

This looks good to me. Is it worth having an _isDelegated() method to handle the duplicated target[ 0 ] !== this.element[ 0 ] check?

[scottgonzalez]

Perhaps. It's a simple check, so it's unlikely to be done wrong and I'm not sure if we'll save any bytes. I'll go with whatever is smaller.

[robotdan]

You beat me to the punch. :-) I have some unit tests that could be added to this if that is helpful. I'm using $._data to get the remove events, perhaps that isn't an ok thing to do in a unit test since that is an internal structure.

[scottgonzalez]

Yeah, I don't want to look at $._data.